1. Field of the Invention
The present invention relates generally to nuclear reactor facilities, and more particularly to a mounting system for a set of four television cameras upon a nuclear reactor refueling machine outer or stationary mast whereby the television cameras can readily scan reactor core fuel assemblies as the same are being vertically removed from the core by means of the refueling machine during the performance of a refueling operation so as to detect the existence, or determine the extent, of any damage to any one of the fuel assemblies or the fuel assembly grid straps, or alternatively, the television cameras can provide remote viewing of the reactor core so as to facilitate insertion of the fuel assemblies into the core during a refueling operation.
2. Description of the Prior Art
As is well known in the nuclear reactor art, fuel, conventionally in the form of pellets, is inserted within suitable cladding material, and the composite assemblage of the fuel pellets and the cladding material or casings define or form the nuclear reactor fuel rods. In turn, a predetermined number of fuel rods, assembled or secured together by means of bands called grid straps, form or define a fuel element or fuel assembly, and a predetermined number of fuel elements or fuel assemblies serve to define or form the nuclear reactor core. As a result of the normal operation of the nuclear reactor facility, the nuclear fuel within the core fuel assemblies naturally becomes depleted, and consequently, the reactor core fuel assemblies must be periodically replaced and refueled. This is achieved by means of conventional refueling operations and techniques.
In particular, the fuel within the reactor core fuel assemblies is depleted over a predetermined period of time and at a predetermined consumption rate such that once an initially new reactor facility has attained its steady state fuel consumption activity or operation through means of having undergone, for example, an initial two-year stabilization period of operation, each fuel assembly utilized within the reactor core will have a service life of three years. In lieu of refueling the entire reactor core once every three years by replacing all of the core fuel assemblies with newly fresh fuel assemblies, maintenance requirements and economic considerations have dictated that the reactor core be refueled once per year, during which period the reactor facility is of course shut down. In order to achieve or accommodate such requisite refueling operations, the reactor core is sectionalized, and the fuel supply relatively staggered between the core sections or stages. Specifically, the reactor core fuel assemblies are effectively arranged within three groups, sections, or stages, including a first, central circular section, a second intermediate annular section disposed about the first central section, and a third outermost annular section disposed about the second intermediate annular section. In addition, as a result of the aforenoted initial two-year stabilization period of operation, at the end of any subsequent one-year period of operation, the nuclear fuel disposed within the fuel assemblies of the innermost or first central section of the reactor core, which fuel assemblies have been disposed within the reactor core for an operational period of three years, will have been substantially entirely depleted. Similarly, the nuclear fuel disposed within the fuel assemblies of the second intermediate or middle section of the reactor core, which fuel assemblies have been in operational service within the reactor core for a period of only two years, will be sufficient so as to permit such fuel assemblies to provide service within the reactor core for an additional period of one year. In a like manner, the nuclear fuel disposed within the fuel assemblies of the third outermost section of the reactor core, which fuel assemblies have been in operational service within the reactor core for a period of only one year, will be sufficient so as to permit such fuel assemblies to provide service within the reactor core for an additional period of two years. In accordance with conventional refueling techniques, then, the fuel assemblies from the innermost or central section of the core are removed from the reactor core for actual refueling with fresh or new fuel, while the fuel assemblies disposed within the intermediate or middle section of the core are transferred to the first central section of the core. Continuing further, the fuel assemblies disposed within the outermost third section of the core are transferred to the second intermediate or middle section of the core, while entirely new or fresh fuel assemblies are inserted into the outermost third section of the core, thereby completing the refueling operation of the reactor facility.
It is imperative that a complete inspection of the entire external peripheral surface area of each fuel assembly and its grid straps be performed at sometime during the performance of the reactor facility refueling operation in order to detect or determine the existence of any damage to the fuel assemblies and/or the grid straps that may have possibly occurred or developed during the previous cyclic operation of the facility, in view of the obviously desirable objective of replacing damaged fuel assemblies within the reactor core so as not to present any possibility of an operational failure within the reactor facility. It is particularly desirable to be able to accomplish the foregoing fuel assembly inspection procedures during the actual refueling processing or handling sequence without considerably prolonging the refueling operation, and without the requirement of any substantial or large-scale modification of existing reactor facility refueling machine apparatus and equipment. Conventional refueling machines comprise a trolley movable within a horizontal plane along a suitable track system disposed above the reactor core at an elevational height of, for example, thirty-five feet, and a vertically disposed outer or stationary mast is fixedly mounted upon the refueling machine trolley so as to be movable therewith. The lower end of the stationary or outer mast is disposed within the reactor core cavity water, and a vertically movable inner mast or gripper tube is co-axially disposed in a relatively telescopic manner interiorly of the outer stationary mast. A gripper assembly is fixedly secured to the lower end of the inner mast or gripper tube for engaging the fuel assemblies in order to perform the aforenoted refueling operation handling sequences, during which the inner mast, the gripper assembly, and the fuel assembly, are retracted internally within the refueling machine outer mast. Conventional refueling machine apparatus and equipment does not in fact exist so as to therefore permit inspection of the fuel assemblies during the underwater handling modes of the refueling operation, and lowering of the water level within the reactor core cavity is certainly not a viable operational alternative in view of the inordinate amount of time that would be required in performance of such a procedural step, as well as performance of the various operational safety sequences attendant thereto, each time a fuel assembly is being removed from, deposited within, or transferred from one position to another position within, the reactor core.
As was noted hereinabove, conventional refueling machines include a trolley movable within a horizontal plane along a suitable track system disposed above the reactor core at an elevational height of, for example, thirty-five feet. The refueling machine operator or personnel control the refueling machine, and perform the refueling operation, from the trolley as a result of observing the reactor core and the various fuel assemblies thereof through means of a suitable viewing aperture or window defined within the refueling machine trolley deck. Consequently, during a refueling operation, when it is desired to insert a particular fuel assembly into a free space of the reactor core, such as, for example, when depositing a fresh or new fuel assembly into the outermost third section of the core or when transferring a fuel assembly from the third or second section of the core to the second or first section of the core, respectively, it may be readily appreciated that considerable difficulty may be encountered by the refueling machine operator or personnel due to the aforenoted distance between the trolley deck and the reactor core. In addition, the reactor core cavity is entirely immersed within water, and consequently, the different light refractive properties of the air environment within which the operator personnel is located and the water environment within which the fuel assemblies are located cause distortion and an apparent erroneous location of the reactor core fuel assembly spacial locations. The refueling operation is therefore considerably impeded, the efficiency of the same accordingly reduced, and the time for completion of the refueling operation correspondingly prolonged.
Accordingly, it is an object of the present invention to provide a new and improved nuclear reactor refueling machine.
Another object of the present invention is to provide a new and improved nuclear reactor refueling machine which will overcome all of the aforenoted disadvantages and drawbacks of conventional nuclear reactor refueling machines and the refueling operations characteristic thereof.
Still another object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit inspection of the entire external surface area of a fuel assembly for the detection and determination of any damage or defects thereof.
Yet another object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit inspection of the entire external surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defect thereof.
Still yet another object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit inspection of the entire external surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defect thereof, without prolonging the handling sequence and the refueling operation.
Yet still another object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit inspection of the entire exterior surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defect thereof, without the necessity of any substantial or large-scale modification of existing refueling machine apparatus or equipment.
A further object of the present invention is to provide a new and improved nuclear reactor refueling machine which will in fact readily permit the visual inspection of the entire external surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defect thereof, by means of substantially simplified modification of existing, conventional nuclear reactor refueling machines.
A yet further object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit the visual inspection of the entire external surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defects thereof, as well as the visual monitoring of such inspection procedures by remotely located personnel.
A still further object of the present invention is to provide a new and improved nuclear reactor refueling machine which will readily permit the visual inspection of the entire external surface area of a fuel assembly during a refueling handling sequence so as to detect and determine the existence of any damage or defects thereof, as well as the tape recording of such visual inspection so as to provide a permanent record thereof.
A yet still further object of the present invention is to provide a new and improved nuclear reactor refueling machine which will greatly facilitate the alignment of the refueling machine and a fuel assembly gripped thereby, and the reactor core spacial location within which the fuel assembly is to be deposited.
A still yet further object of the present invention is to provide a new and improved nuclear reactor refueling machine which will provide the refueling machine operator or personnel with a clear and unobstructed view of the particular reactor core spacial location within which a fuel assembly is to be deposited.
An additional object of the present invention is to provide a new and improved nuclear reactor refueling machine which will permit the refueling machine operator or personnel, who is positioned at a location within the reactor facility which is remote from the reactor core, to view the particular reactor core spacial location within which a fuel assembly is to be deposited from a vantage point which is effectively within the immediate vicinity of the reactor core and the spacial location.